Improving soil resistance through the use of rare earth metal containing compounds

ABSTRACT

A process of improving the soil resistance of polyamide, acrylic, and polyester fiber through impregnating the fiber with an aqueous solution containing a rare earth metal halide, drying the impregnated fiber, and impregnating the dried fiber with a reagent to form a substantially aqueous insoluble rare earth metal compound.

aiem

Hirshield et a1.

[ Feb. 29, 1972 [54] IMPROVING SOIL RESISTANCE THROUGH THE USE OF RARE EARTH METAL CONTAINING COMPOUNDS [72] Inventors: Julian J. Hirshield; Bertie J..Reuben, both of Decatur, Ala.

[73] Assignee: Monsanto Company, St. Louis, Mo.

[22] Filed: Aug. 8, 1966 [21 App1.No.: 570,777

1,914,059 6 /1 9 33 vvh m r1 1 43 x 2,323,387 7/1943 Edelstein ..117/169 2,631,110 3/1953 Van Norden ...1 17/169 X 2,786,787 3/1957 Florio ..1 17/169 2,788,295 4/1957 Cooke et al.... 117/143 X 2,551,175 5/1951 Smith 210/508 X 3,105,500 10/1963 Wilson et al. 17/98 X 3,382,985 5/1968 Muehl ..210/499 X Primary ExaminerWilliam D. Martin Assistant Examiner-Theodore G. Davis AttorneyRobert L. Broad, Jr. and Roy P. Wymbs [57] ABSTRACT A process of improving the soil resistance of polyamide, acrylic, and polyester fiber through impregnating the fiber with an aqueous solution containing a rare earth metal halide, drying the impregnated fiber, and impregnating the dried fiber with a reagent to form a substantially aqueous insoluble rare earth metal compound.

14 Claims, N0 Drawings SOIL RESISTANCE THROUGH THE USE OF RARE EARTH METAL CONTAINING COMPOUNDS This invention relates to improvements in the antisoiling properties of synthetic fibers and fibrous materials. More specifically, this invention relates to improvements in the antisoiling characteristics of fibrous materials through the use of rare earth metal containing compounds.

The compounds contemplated in the present invention are effective to improve the resistance to soiling of fibrous materials, and are particularly adaptable to pile fabrics.

,With the onslaught of synthetic fibers, a real nuisance emerged in terms of soiling. There are many different theories involved in the explanation of the soiling phenomena, but there has not been available a suitable solution for the problem. Also, due to the widespread usage in recent years of pastel colors and rugs made of synthetic fibers, the textile industry has felt an increasing need for effective soil retardants. Synthetic fibers soil more readily than natural fibers, and the use of pastel colors enhances the appearance of soiling. Numerous processes and soil retardant compounds and compositions have become available in response to the growing demand, but none have been absolutely satisfactory. These materials have come both from the organic and inorganic classes and have both suffered from various limitations, such as harshness of hand, dusting, limited drying temperatures, discoloration, expense, washing problems, etc. With regard to expense, both the cost of the material and the'process costs chloride 7 Lanthsnum as La Cl, 611,0 24.0 Cerium as Ce Cl, 611,0 45.2 Praseodymium as Pr Cl, 6H,O 4.9 Neodymium as Nd Cl, til-1,0 16.5 Samarium as Sm Cl, 6H,0 2.9 Gadolinium (approx.) as Gd Cl, 611,0 2.0 Yttium (approx.) as Y Cl,- 611,0 0.3 Other rare earths (approx.) as R Cl, 61-1,0 0.8 (R rare earth) Total 96.6

have been excessive. Often various steps of the process call for different materials, or for reacting various materials prior to application while various interim steps are filled with washing and drying procedures. As to discoloration, this can be caused by either the material used or the temperature to which the fabric is subjected during the treatment.

Accordingly, the difficulties of the prior. art are overcome by treating (impregnating) fibrous materials with a rare earth metal containing compound, followed by rinsing and drying.

It is, therefore, an object of this invention to provide a method of improving the resistance to soiling of fibrous materials through the use of rare earth metal containing compounds.

Another object of this invention is to provide an inexpensive and simple process of improving the resistance to soiling of fibrous materials.

Further, it is an object of this invention to provide a method of improving the resistance to soiling of fibrous materials which does not affect the hand" of the treated material.

Also, an object of this invention is to provide a composition for improving the resistance to soiling of fibrous materials which does not adversely affect the color, and which in many cases brightens the material.

These and other objects and advantages will become more readily apparent when read in conjunction with the following detailed description.

In accordance with the present invention, it has been found that fibrous materials comprised of synthetic fibers can be rendered highly soil resistant through a simple application of rare earth metal containing compounds. As used in this invention, the term fiber" connotes and comprises both staple and continuous filaments.

1n the preparation of retardant compositions to produce soil resistant fibrous materials, rare earth metal containing compounds may exist in solution from a minimum of about 0.5 percent to a maximum determined only by economic conditions. Optimum results exist at different percentages for different fibers, i.e., polyamide, polyester, acrylic, etc. When rare earth metal chloride is used to improve the resistance to soiling of polyamide, polyester, and acrylic fibrous materials, it is estimated that it is best to use at least about a 2 percent solution.

Rare earth metal chloride referred to in this application has the following composition:

Rare earth composition Rare earth metals rare earth metal Reflectance measurements are used to illustrate the antisoiling properties imparted to fibrous materials after the materials have been treated in accordance-with the invention. More specifically, two samples (2 inches 4 inches) of the material are used to determine a value for each test. Photo reflectance measurements are derived from each of the two samples and averaged. This average value is the reflectance value for the material in question. The measuring apparatus is a Photovolt Reflectance Meter (Model No. 610, Photovolt Corporation, New York, New York). Thereafter, the two samples of the material are soiled by either of two methods. One method is the artificial soiling test which is accomplished by placing-the two samples in a one gallon wide mouth jar having therein two glass rods (5% inches long by three-eighths inch diameter), artificial soil, and 10 No.2 rubber stoppers. The artificial soil has the following composition (the soil is sifted through a 30-mesh screen):

Peat Moss 22.3% Silica gel 2.1% Cement 2.1% Kaolin clay (peerless) 2.1% Molacco furnace black 0.2% Red iron oxide 0.1% Sawdust 52.5% Calcium carbonate 10.9% Animal charcoal 6.6% Mineral oil 1.1%

Total 100.0%

The jar is then sealed, placed on a ball mill frame and rotated at -100 rpm. for 30 minutes in a clockwise direction and then 30 minutes in a counterclockwise direction. Thereafter, the two samples are removed from the jar, vacuumed, and the photo reflectance of the two samples is again measured and averaged. The difference in the average initial reflectance measurements and the average final reflectance measurements indicates the extent of soil resistance. A small difference in the reflectance indicates a poor antisoiling property of the material. The other method is the floor soiling test and the procedure is the same as the artificial soiling test except the samples are soiled by placing them in the path of a well travelled walkway and soiled by natural means, such as shoes, etc. Control samples (samples which are not treated with rare earth metal containing compounds are soiled in the same manner as the test samples with averages being taken. The results of the control samples are compared and contrasted with the test samples whereby the significance of the invention may be ascertained. Where the samples of the fibrous materials are carpet samples, they are usually soiled by subjecting them to the floor soiling test. This type of testing renders theory almost actuality.

Rare earth metal containing compounds may be applied to the material (or the material may be treated or impregnated) in any number of ways. Padding and exhaust are probably the two methods which will be used in most cases. In the padding process the fibrous material is passed through or immersed in,

a bath of an aqueous solution containing a rare earth metal liquid, followed by drying. 1t is a continuous process readily adaptable to fiber treatment on thespinning machine. In the exhaust treatment, the material is immersed in an aqueous solution of the rare earth metal containing compound and boiled for about 30 minutes. The two methods give essentially equal results.

The following examples will illustrate the different effects upon different materials under various conditions. An'important thing to note in the following examples with regard to some initial dulling upon application of the rare earth metal containing compounds is the percent brightness loss" and the' difference A." Even though the material is slightly dulled initially, this is not considered either a technical of commercial disadvantage. From the practical standpoint of customer satisfaction, it is of primary importance that the material retain its original appearance during use with a minimum in apparent difference between areas subjected to soiling and areas not subjected to soiling. It is also worth noting that a difference of 2 or 3 units is visually significant on a comparative basis with regard to the difference A values. The essence of the invention is to impart soil resistance to fibrous materials, i.e., reduce the apparent amount the material will soil.

Various procedures for treating the fibrous materials are illustrated in the examples which show that the test and control samples were treated in the same way except the control samples were not subjected to the salt treatment. The particular pretreatment (scouring, drying, etc.) will be set out in the examples. After treatment the samples were subjected to laboratory accelerated soiling associated with other testing.

When used, the standard scour for polyamide and acrylic samples comprised 0.5 percent on the weight of the material (o.w.g.) lgepal CO-7l0 (a nonionic surfactant marketed by General Aniline and Film Corporation )and 0.5 percent on the weight of the goods tetrasodium pyrophosphate with the samples entering the bath at 160 F. and run for 30 minutes. The samples were removed and rinsed in cold water and dried. The standard scour for polyester samples comprised 6 g./l. Varsol (Kerosene), 1 g./l. caustic soda, and l g./l. lgepal CO-630 (a nonionic surfactant marketed by General Aniline and Film Corporation) with the samples entering the bath at 200 F. for 20 minutes. The samples were then removed and rinsed with warm water and dried.

When used, blank dyeing for polyamide samples was effected by treating with 0.5 percent on the weight of the material (o.w.g.) with lgepal CO-710 with the samples entering the bath at room temperature and raised to a boil (about 30 minutes) and boiled for 60 minutes. The samples were then removed, rinsed, and dried. The acrylic fiber samples composed of 76.5 percent of a copolymer being 93 percent acrylonitrile and 7 percent vinyl acetate. 10.5 percent of a copolymer being 50 percent acrylonitrile and 50 percent methyl vinyl pyridine, and 13 percent polyvinyl chloride were treated with 5 percent (o.w.g.) Glaubers Salt (sodium sulfate), 3 percent (o.w.g.) urea, and 0.5 percent (o.w.g.) lgepal C-710. The acrylic fiber samples composed of a copolymer containing 93 percent acrylonitrile and 7 percent vinyl acetate were treated with percent (o.w.g.) Glaubers Salt, 0.5 percent (o.w.g.) acetic acid. Both acrylics were then treated identically with the samples entering the bath at room temperature and being raised to boil (about 30 minutes) and boiled for 60 minutes. The samples were then rinsed and dried. Blank dyeing of polyester involved subjecting the sample to 8 g./l. Carolid (a self-emulsifiable modified phenol derivative marketed by Tanatex Chemical Corporation), 0.5 percent (o.w.g.) lgepon T-51 (an anionic detergent marketed by General Aniline and Film Corporation), and enough acetic acid until the pH reached 5.5. Thereafter, the polyester samples were treated the same as were the acrylics.

After the blank dyeing procedure was completed, the samples were subjected to laboratory soiling and evaluated for difference in reflectance.

Rare earth metal chlorides were used to improve the resistance to soiling in the following examples. The rare earths cover elements from Lanthanum No. 57 to Lutetium No. 71 and are also called the, Lanthanum series. Because of their extremely close chemical similarity, they can be considered and applied as one entity.

Highly purified separate individual rare earths metals are very rare and expensive. Most applications of rare earth metals, as with this invention, do not require such extreme purities, and therefore, rare earth metal chlorides and halides are sufficient. The added expense is not justified at present-day costs, but the use of pure individual rare earth metal salts is considered within the realmof this invention.

The rare earth metal chlorides may be converted after they have been applied to the material into rare earth metal compounds such as substantially aqueous insoluble carbonates, fluorides, phosphates, etc. by reacting with reagents such as sodium carbonate, lithium fluoride, pyrophosphate, etc. The increased costs associated with producing insolubles is justified because the soil resistance imparted to the fibrous material will have a longer lasting effect and will not wash away as readily upon cleaning, nor wear away as readily with everyday use.

The following table gives the rare earth metal compounds or products which result from reacting rare earth metal chloride with various reagents. 3

Regent Substantially insoluble rare earth metal products (R=rare rare metals) Alkalis Hydroxide: or basic chlorides Alkali and ammonium carbonates Carbonates and bicarbonates Alkali phosphate Phosphates R PO,- XH,O Hydrogen fluoride, lithium and water soluble fluorides Alkali and ammonium sulfates Alkali sulfates R,(SO,), Na,S0,

2H,0 (sparingly soluble) Soaps-stearate, oleate,

linoleate, naphthenate, etc. (generally soluble in nonpolar organic solvents) To obtain a better insight into the invention, some of the tests in the following examples were conducted on material carrying the spin finish, whereas other tests were conducted on the same material where the spin finish had been removed. The spin finish is the conventional lubricating and antistatic finish applied to the fiber during manufacture to facilitate handling and processing.

In order that the present invention may be more fully understood, the following examples are given primarily by way of illustration. No details appearing therein should be construed as limitations on the invention, except as they appear in the appended claims.

Alkali soaps of fatty acids, naphthenates, etc.

EXAMPLE 1 Acrylic fiber swatches (knit tapes) composed of a copolymer containing 93 percent acrylonitrile and 7 percent vinyl acetate were subjected to the following 5 tests with the results appearing in Table 1 below. The swatches (both control and treated) had been scoured and rinsed prior to running the tests.

A. Tapes were padded with a 2 percent solution, based on the weight of material (o.w.g.) of rare earth metal chloride, dried, immersed (impregnated) in a 5 percent solution (o.w.g.) of sodium carbonate for 10 minutes, rinsed, and dried. The sodium carbonate converted the rare earth metal chloride into a substantially aqueous insoluble rare earth metal carbonate as denoted generally by the following formula: R C1 611 0 Na CO R (CO )B3 XH O tetrasodium B. Tapes were padded with a 2 percent (o.w.g.) solution of EXAMPLE I]! rare earth metal chloride, dried, immersed in 5 percent (o.w.g.) sodium hydroxide for 10 minutes, rinsed and dried. Here the sodium hydroxide converts the rare earth chloride into a substantially aqueous insoluble rare earth 5 metal hydroxide denoted generally by the following formula: R Cl GH O NaOll-l R(Ol l) C. Tapes were padded with a 2 percent solution (o.w.g.) of

Acrylic fiber swatches composed of 76.5 percent of a copolymer being'93 percent acrylonitrile and 7 percent vinyl acetate, 10.5 percent of a copolymer being 50 percent acrylonitr'ile and 50 percent methylvinylpyridine, and 13 percent polyvinyl chloride were treated in the same way as were the acrylic samples in Example l.

rare earth metal chloride, dried gently, immersed in 5 10 TABLE3 percent (o.w.g.) lithium fluoride for 10 minutes, rinsed, and dried. The rare earth chloride was converted into an insoluble fluoride. R Cl -6H O-l-LiF RF XH O Acrylic Fiber D. Tapes were padded with a 2 percent (o.w.g.) solution of (Mm i: n t M 8mm t rare earth chloride, dried, and rinsed. 15 Before R ga y s b Brighmess E. Tapes were padded with a 2 percent (o.w.g.) solution of Test rare earth chloride, dried, immersed in a 5 percent soiling soiling A LOSS (o.w.g.) solution of tetrasodium pyrophosphate for 10 g g; i; 2: minutes, rinsed, and dried. The rare earth chloride was 3 54 25 29 54 converted into an insoluble phosphate. R Cl 6H O+ C 53 27 26 49 Na P O RPO- Xl-I O D 51 f F. Tapes were padded with a 2 percent (o.w.g.) solution of E 53 27 53 rare earth metal chloride, dried, immersed in a 5 percent (o.w.g.) solution of phosphoric acid for 10 minutes, rinsed, and dried. The rare earth chloride was converted 25 EXAMPLE IV ggbj igz g Phosphate R Ch Q H Acrylic fiber swatches described in Example I]! were G. Tapes were padded with a 2 percent (o.w.g.) solution of treated as desgnated m Example rare earth metal chloride, dried, immersed in a 5 percent 30 TABLE 4 (o.w.g.) solution of oxalic acid for 10 minutes, rinsed, and dried. The rare earth chloride was converted into an insoluble oxalate. R Cl 6H O 11 C 0 R (C O,,) Acrylic Fiber z (After S'couring & Blank Dyeing) Reflectance Measurements TABLE I Before After Difference Brightness Test Soiling Soiling A Loss A l' F'b ig 'f l g Control s4 17 37 69 Reflectance Measurements 40 A 53 2o 33 62 Before After Difference Brightness B 53 I7 36 68 Test 0 53 i9 34 64 D 51 18 33 65 Sailing Soiling A Loss E 53 I9 34 64 Control 69 27 42 61 45 A 67 36 31 46 r B 67 3s 34 51 C 69 as 33 48 EXAMPLE v E Z: :2 g Polyester fiber swatches were treated in the same way as F 70 39 31 44 50 were the acrylic swatches in Example I with the results appear- 0 69 as 33 43 mg m Table 5 below.

TABLE 5 Polyester Fiber EXAMPLE H (After Rinsing) Reflectance Measurements Acrylic fiber knit tapes described in Example I were treated Before Dmmm Brightness as designated in Example I. Here the tapes were scoured and Test blank dyed prior to being treated. soiling Selling A Loss TABLE 2 Control 79 2s 5s 67 A 77 29 48 62 a 77 30 47 6| c 78 30 4a 62 Acrylic Fiber D 77 32 45 55 (After Rinsing & Blank Dyeing) E 77 3| 46 50 Reflectance Measurements 65 F 3 3g 30 44 After Before Difference Brightness G 74 43 31 42 Test Soiling Soiling A Loss Control 67 27 40 60 EXAMPLE VI A 66 s4 32 4s 70 B as 30 36 55 Polyester fiber swatches were treated in the same way as c 35 were the acrylic fiber swatches in Example ll. 0 s7 33 34 51 F 66 34 32 V 48 TABLE 6 Polyester Fiber (After Scouring & Blank Dyeing) Reflectance Measurements Polyamide (nylon 66) fiber swatches were treated in the same way as were the acrylic fiber swatches in Example I.

Polyamide fiber swatches were treated in the same way as were the acrylic fiber swatches in Example II.

TABLE 8 Polyamide Fiber (After Scouring & Blank Dyeing) Reflectance Measurements Before After Difference Brightness Test Soiling Soiling A Loss Control 84 I9 65 77 EXAMPLE IX Acrylic fiber swatches (knit tape) composed of a copolymer containing 93 percent acrylonitrile and 7 percent vinyl acetate were subjected to the following tests with the results appearing in Table 9 below. The spin finish was on the tapes at the time of the tests.

A. Tapes were immersed in an aqueous solution (bath) containing 5 percent (o.w.g.) rare earth metal chloride which was at ambient temperature. The temperature of the bath was raised to 160 F. and then 5 percent (o.w.g.) potassium fluoride was added. The temperature of the bath was then raised to 180 F. and held there for 30 minutes. The tapes were removed from the bath, rinsed and dried. The rare earth chloride was converted into an insoluble fluoride.

R Cl 6H O+ KF RF XH O B. Tapes were immersed in an aqueous solution (bath) containing 5 percent (o.w.g.) rare earth metal chloride which was at ambient temperature. The temperature of the bath was raised to F. and 5 percent (o.w.g.) tetrasodium pyrophosphate was added. The temperature of the bath was then raised to F. and held for 30 minutes. The tapes were removed from the bath, rinsed, and dried. The rare earth chloride was converted into an insoluble phosphate. R Cl; 6H O+ Na P,O-, R PO, X11 0 C. Tapes were immersed in an aqueous solution containing 5 percent (o.w.g.) rare earth metal chloride which was at ambient temperature. The temperature was raised to the boiling point and held to 30 minutes. The tapes were removed, rinsed, and dried.

D. Tapes were padded with an aqueous solution containing 2 percent (o.w.g.) rare earth metal chloride, dried gently, treated with an aqueous solution containing 5 percent (o.w.g.) potassium fluoride for 10 minutes, rinsed, and

dried. An insoluble fluoride resulted as in A) above.

E. Tapes were padded with an aqueous solution containing 2 percent (o.w.g.) rare earth metal chloride, dried gently, treated with an aqueous solution containing 5 percent (o.w.g.) tetrasodium pyrophosphate for 10 minutes, rinsed, and dried. The rare earth chloride was converted into an insoluble phosphate as in B) above- TABLE 9 Acrylic Fiber With Spin Finish (After Rinsing) Reflectance Measurements Before After Difference Brightness Test Soiling Soiling A Loss Control 64 16 48 75 c 64 2s 39 at E as I 29 36 5s EXAMPLE X Acrylic fiber swatches described in Example IX were treated as designated in Example lX, but the treatment occurred after scouring and blank dyeing.

TABLE 10 Acrylic Fiber With Spin Finish (After Scouring & Blank Dyeing) Reflectance Measurements Acrylic fiber swatches composed of 76.5 percent of a copolymer being 93 percent acrylonitrile and 7 percent vinyl acetate, 10.5 percent of a copolymer being 50 percent acrylonitrile and 50 percent methylvinylpyridine, and 13 percent polyvinylchloride were treated in the same way as were the acrylic swatches in Example IX TABLE 1 l Acrylic Fiber With SpiriFinish Acrylic fiber swatches described in Example XI were treated as designated in Example IX, but after scouring and blank dyeing. The results appear in Table 12 below.

Table 12 Acrylic Fiber With Spin Finish (After Scouring 8t Blank Dyeing) Reflectance Measurements Before After Difference it: Brightness Test Soiling Soiling A Loss Control 7 21 36 63 A 56 23 33 59 B 57 23 34 60 C 55 22 33 60 EXAMPLE XIII Polyester fiber knit tapes (swatches) were treated in the same way as were the acrylic swatches in Example IX.

TABLE 13 Polyester Fiber With Spin Finish (After Rinsing) Reflectance Measurements Polyester fiber swatches were treated in the same way as were the polyester swatches in Example XV, but the treatment occurred after scouring and blank dyeing.

TABLE 14 Polyester Fiber With Spin Finish (After Scouring & Blank Dyeing) Reflectance Measurements Before After Difference Brightness Test Soiling Soiling A Loss Control 75 27 48 64 EXAMPLE xv Polyamide fiber swatches were treated in the same way as were the acrylicfiber swatches in Example l)( were theresults appearing in Table 15 below.

TABLE I5 Polyamide Fiber With Spin Finish (After Rinsing) Reflectance Measurements Before After Difference b Brightness Test Soiling Soiling A Loss Control 75 I7 58 77 A SI 25 56 69 I C 8l 23 58 72 D Bl 24 57 70 E 80 29 SI 64 EXAMPLE XVI Polyamide fiber swatches were treated in the same way as were the polyamide swatches in Example XV, but the treatment occurred after scouring and blank dyeing.

TABLE 16 Polyamide Fiber With Spin Finish (After Scouring & Blank Dyeing) Reflectance Measurements 1. A process of improving the resistance to soiling of a synthetic fibrous material comprised of fiber selected from the group consisting of acrylic fiber, polyamide fiber, and polyester fiber comprising impregnating the material with an aqueous solution containing a rare earth metal containing compound.

2. A process according to claim I wherein the rare earth metal containing compound is a rare earth metal halide.

3. A process according to claim 1 wherein the aqueous solution contains above about 0.5 percent, based upon the weight of the material, of a rare earth metal halide.

4. A process according to claim 1 wherein the material is impregnated at a temperature above about ambient temperature.

5. A process of improving the resistance of soiling of a synthetic fibrous material comprised of fiber selected from the group consisting of acrylic fiber, polyamide fiber, and polyester fiber comprising impregnating the material at a temperature above about ambient temperature with an aqueous solution containing above about 0.5 percent, based upon the weight of the material, of a rare earth metal halide.

6. A process according to claim 5 wherein the material is dried after being impregnated with the solution containing a rare earth metal halide and then impregnated with a reagent whereupon the chloride is displaced from the rare earth metal and a rare earth metal compound is formed which is substantially aqueous insoluble.

7. A process of improving the resistance to soiling of a synthetic fibrous material comprised of fiber selected from the group consisting of acrylic fiber, polyamide fiber, and polyester fiber comprising the steps of:

a. impregnating the material at a temperature above about ambient temperature with an aqueous solution containing above about 0.5 percent, based on the weight of the material, of a rare earth metal halide; and

b. impregnating the rare earth metal halide impregnated material with a reagent whereupon 'a substantially aqueous insoluble rare earth metal compound is formed.

8. A process according to claim 7 wherein the reagent is selected from the group consisting of alkalis, alkali and ammonium carbonates and bicarbonates, fluorides, ammonium sulfates, phosphoric acid, sulfuric acid, nitric acid, oxalic acid, alkali soaps of fatty acids, and alkali soaps of naphthenates.

9. A process according to claim 7 wherein the reagent is selected from the group consisting of alkalis, alkali and ammonium carbonates and bicarbonates, alkali phosphates, hydrogen fluoride, lithium fluoride, soluble fluorides, alkali sulfides, oxalic acid, and phosphoric acid.

10. A process according to claim 7 wherein the reagent is selected from the group consisting of sodium carbonate, sodium hydroxide, lithium fluoride, tetrasodium pyrophosphate, phosphoric acid, oxalic acid, and potassium fluoride.

11. A process according to claim 7 wherein the rare earth metal halide impregnated material is impregnated with the reagent for a time sufficient for the halide to be displaced from the rare earth metal halide whereupon a substantially aqueous insoluble rare earth metal compound is formed.

12. A process according to claim 7 wherein the rare earth metal halide is a rare earth metal chloride.

13. A process according to claim 7 wherein the rare earth metal halide impregnated material is dried before being impregnated with the reagent.

14. A process of improving the resistance to soiling of a synthetic fibrous material comprised of fiber selected from the group consisting of polyamide fiber, acrylic fiber, and polyester fiber, comprising the steps of:

a. impregnating the material at a temperature above about ambient temperature with an aqueous solution containing above about 0.5 percent, based upon weight of the material, of a rare earth metal chloride;

b. drying the rare earth metal chloride impregnated material; and

c. impregnating the dried material with a reagent selected from the group consisting of sodium carbonate, sodium hydroxide, lithium fluoride, tetrasodium pyrophosphate, phosphoric acid, oxalic acid,'and potassium fluoride, for a time sufficient for the chloride of the rare earth metal chloride to be displaced whereupon a rare earth metal compound is formed which is substantially aqueous insoluble.

Patent No. 3,645,780v Da February 29, 1972 Inventor(s.) Julian J. Hirshfeld, and Bertie J Reuben It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 3, line 40, after "200 F. "insert -and being run Col. 3, line 46, cancel "and" and substitute With the bath then being;

C01. 3, line 49., "being" should read of;

C01. 3, line 51, "being" shoul'dread '-'Of--;-

Col. 4, line 26, the olumn headings should read -Reagent and Substantially insoluble rare earth metal products (R rare earth metals)" instead of "regent" and "Substantially insoluble rare earth metal products (R=rare rare metals)", respectively.

Col. 4, Under the column "Reagent" the fourth reagent listed should read Hydrogen fluoride, lithium fluoride, and water soluble fluoride s".

XH O" in the column of This should be aligned with "Fluorides RF rare earth metal compounds.

FORM PC4050 (10459) USCOMM-DC 6O376-P69 & U.5. GOVERNMENT PRINTING OFFCE: I969 0-366-33 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,645,780 Dated February 29, 1972 lnvent'ofls) Julian J. I-Iirshfeld and Bertie J. Reuben PAGE 2 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 4, last two lines, "RG1 should read RC1 6H2O Na CO Col. 6, line 4, "being" should read -of"--.

R (CO XH O Signed and sealed this th day of July 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK 1 Attestlng Officer Commissioner of Patents USCOMM-DC 6037 6-P69 U S. GOVERNMENT PRINTING OFFICE: I969 0-366-334 FORM PO-105O (10-69) 

2. A process according to claim 1 wherein the rare earth metal containing compound is a rare earth metal halide.
 3. A process according to claim 1 wherein the aqueous solution contains above about 0.5 percent, based upon the weight of the material, of a rare earth metal halide.
 4. A process according to claim 1 wherein the material is impregnated at a temperature above about ambient temperature.
 5. A process of improving the resistance of soiling of a synthetic fibrous material comprised of fiber selected from the group consisting of acrylic fiber, polyamide fiber, and polyester fiber comprising impregnating the material at a temperature above about ambient temperature with an aqueous solution containing above about 0.5 percent, based upon the weight of the material, of a rare earth metal halide.
 6. A process according to claim 5 wherein the material is dried after being impregnated with the solution containing a rare earth metal halide and then impregnated with a reagent whereupon the chloride is displaced from the rare earth metal and a rare earth metal compound is formed which is substantially aqueous insoluble.
 7. A process of improving the resistance to soiling of a synthetic fibrous material comprised of fiber selected from the group consisting of acrylic fiber, polyamide fiber, and polyester fiber comprising the steps of: a. impregnating the material at a temperature above about ambient temperature with an aqueous solution containing above about 0.5 percent, based on the weight of the material, of a rare earth metal halide; and b. impregnating the rare earth metal halide impregnated material with a reagent whereupon a substantially aqueous insoluble rare earth metal compound is formed.
 8. A process according to claim 7 wherein the reagent is selected from the group consisting of alkalis, alkali and ammonium cArbonates and bicarbonates, fluorides, ammonium sulfates, phosphoric acid, sulfuric acid, nitric acid, oxalic acid, alkali soaps of fatty acids, and alkali soaps of naphthenates.
 9. A process according to claim 7 wherein the reagent is selected from the group consisting of alkalis, alkali and ammonium carbonates and bicarbonates, alkali phosphates, hydrogen fluoride, lithium fluoride, soluble fluorides, alkali sulfides, oxalic acid, and phosphoric acid.
 10. A process according to claim 7 wherein the reagent is selected from the group consisting of sodium carbonate, sodium hydroxide, lithium fluoride, tetrasodium pyrophosphate, phosphoric acid, oxalic acid, and potassium fluoride.
 11. A process according to claim 7 wherein the rare earth metal halide impregnated material is impregnated with the reagent for a time sufficient for the halide to be displaced from the rare earth metal halide whereupon a substantially aqueous insoluble rare earth metal compound is formed.
 12. A process according to claim 7 wherein the rare earth metal halide is a rare earth metal chloride.
 13. A process according to claim 7 wherein the rare earth metal halide impregnated material is dried before being impregnated with the reagent.
 14. A process of improving the resistance to soiling of a synthetic fibrous material comprised of fiber selected from the group consisting of polyamide fiber, acrylic fiber, and polyester fiber, comprising the steps of: a. impregnating the material at a temperature above about ambient temperature with an aqueous solution containing above about 0.5 percent, based upon weight of the material, of a rare earth metal chloride; b. drying the rare earth metal chloride impregnated material; and c. impregnating the dried material with a reagent selected from the group consisting of sodium carbonate, sodium hydroxide, lithium fluoride, tetrasodium pyrophosphate, phosphoric acid, oxalic acid, and potassium fluoride, for a time sufficient for the chloride of the rare earth metal chloride to be displaced whereupon a rare earth metal compound is formed which is substantially aqueous insoluble. 